Return Customer's Quota Usage through Admin API

DocImpact: This patch adds an extension 'UsedLimitsForAdmin'. If this
extention is enabled then it extends the used limits API behavior, such
that admin can fetch the details of any customer's quota usage by passing
the customer's tenant id in query parameters.The API signature for the
same is 'v2/{tenant_id}/limits?tenant_id={customer_tenant_id}'

Change-Id: I89b8b5083e46b899458407426c89a3865e960faa
Implements: blueprint customer-quota-through-admin-api
correctly set iface-id in vmware driver

bug 1183452

Commit 70c659059b8fbef811ce79700aecb01c60242ebd updated the vmware
driver to use the new vif model, but was incorrect in how it tried to
grab the iface-id and set it in the vmx file spec.  This patch fixes
that issue and adds a check for this in the existing unit tests.

Change-Id: I756539871d1844a828f9a0a295fc9fa3e59610f7
Merge "Return Customer's Quota Usage through Admin API"
Merge "correctly set iface-id in vmware driver"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp